Mixing tube for gases



March 1, 1966 J. A. TURNER, JR

MIXING TUBE FOR GASES Filed Nov. 22, 1961 N 0 A N r1 m M A ,T m 0a w W 4 2 3 3 3 3 1 w M I114 n m l I United States Patent M 3,237,923 MIXING TUBE FOR GASES James A. Turner, Jr., 810 Gesco St., Charlotte, N.C. Filed Nov. 22, 1961, Ser. No. 154,172 3 Claims. (Cl. 259-4) The present invention generally relates to a device for mixing two or more gases and more particularly relates to a mixing tube inserted into a gas receiving cylinder.

The primary object of the present invention is to provide a mixing tube for effectively mixing two or more gases disposed in a compressed gas cylinder.

In the compressed gas industry, considerable difiiculty exists when two or more gases of dilierent densities and having different properties are inserted into the same cylinder. When using the cylinder having two or more gases therein, it is necessary that the mixture of the gases therein, it is necessary that the mixture of the gases within the cylinder be substantially homogeneous. This has been heretofore accomplished by tumbling or rolling the cylinder in order to agitate the gases therein for purposes of providing an effective mixing of the gases. Another procedure for mixing the gases which has been resorted to is the addition of heat or the cooling of the outside of the cylinders to assist the gases in raising or lowering themselves within the cylinder whichever may be required. This is sometimes accomplished by placing the cylinder partially in dry ice or hot water or in a combination of the two for the purposes of mixing the gases therein. It is extremely difficult to mix two different gases of equal or different weights and percentages of gases used without some external assistance, which is not only time consuming but also sometimes results in injury and the creation of hazardous situations in the event the compressed cylinders are dropped which could lead to rupture of the cylinder or injury to persons in the area.

In view of the problems existent in the industry in mixing the gases of differing densities, molecular weights, physical properties and the like within a compressed gas cylinder, it is the primary object of the present invention to provide a mixing tube which is connected directly to the valve orifice which normally feeds the gas into the cylinder, the tube extending substantially to the bottom of the cylinder and being provided with a plurality of outlet holes or orifices located in longitudinally spaced relation therealong for discharging the gases into the cylinder at a plurality of predetermined points spaced longitudinally of the cylinder and also dispensing the gas in the same manner. When using the mixing tube, two or more different types of gases are received in the cylinder under pressure from all discharge orifices in the tube. When a second or additional gas is added to the gas already in the cylinder, this additional gas is then discharged again under pressure through the tube in the same manner as in connection with the original gas thus providing a uniform discharge of the gas throughout the length of the tube thus effective-1y mixing the gases with the mixing occurring in a uniform manner from the top to the bottom of the tube or cylinder wherein the high velocity stream of high pressure gas discharged from the various orifices will impinge against the interior wall of the cylinder for causing a mixing action in the cylinder which gives a thorough blend of the gases therein.

Still another object of the present invention is to provide a mixing tube for use in combination with a compressed gas cylinder which will provde an extremely accurate blend of gases regardless of the percentages thereof without any bumping or rolling of the cylinder or without the application of heat or cold treatment to the 3,237,923 Patented Mar. 1, 1966 cylinder and which is quite simple in construction, easy to install, effective in operation and generally inexpensive to manufacture.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a side elevational view of the mixing tube illustrating the manner in which it is installed in a compressed gas cylinder, the cylinder being shown in section;

FIGURE 2 is a perspective view of the mixing tube and valve assembly connected thereto;

FIGURE 3 is a vertical sectional view, on an enlarged scale, taken substantially upon a plane passing along section line 33 of FIGURE 2 illustrating the structural details of the mixing tube; and

FIGURE 4 is a transverse, sectional view, on an enlarged scale, taken substantially upon a plane passing along section line 44 of FIGURE 1 illustrating further structural details of the mixing tube.

Referring now specifically to the drawings, the numeral 10 generally designates the mixing tube of the present invention which is used in combination with a conventional compressed gas cylinder 12 having a concave or recessed bottom 14 and a reduced neck 16 receiving a conventional control valve 18 including a gas inlet and outlet threaded fitting 20, a control handle or knob 22 for operating the valve, and a safety disk 24 in the form of a safety or blowout disk in the event of fire or in the event the gas in the cylinder becomes heated to a point the pressure would increase beyond a safety range and the disk would then blowout to release the pressure in the cylinder. The valve 18 is of conventional construction and is threaded into the neck 16 in the usual manner. For this purpose, the bottom end of the valve 18 is provided with a threaded stem 26 threaded into the neck 16. The valve 18 also has a longitudinal bore 28 communicating with the bottom thereof which normally communicates with the interior of the gas cylinder 12. For the purposes of this invention, the lower end of the bore 28 is internally threaded for receiving the threaded end 30 of the mixing tube 10.

The mixing tube 10 includes an elongated tube 32 of stainless steel or the like such as a /8" stainless steel tube which extends substantially to but terminates in slightly spaced relation to the bottom 14.

Disposed in longitudinally spaced relation in the tube is a plurality of pairs of holes 34 forming orifices for passage of gas. The holes are preferably in diameter and the holes are arranged in pairs with the holes in each pair being diametrically opposed and the holes in adjacent pairs being staggered in relation to each other. The bottom of the tube is provided with a closure plug 36 which also has a orifice or opening 38 formed therein for purposes of passage of the gases therethrough.

This arrangement is highly adaptable for use with various types of gases such as normally supplied in compressed gas cylinders, sometimes referred to as bottles or tanks having pressures varying from 1 p.s.i. to 3,500 p.s.i. Some of the gases which may be effectively mixed with the present invention include argon and oxygen, carbon dioxide and oxygen, nitrogen and oxygen, nitrogen, oxygen and carbon dioxide, nitrogen and hydrogen, argon and hydrogen, helium and oxygen, nitrous oxide and carbon dioxide, and other gases in liquid and gaseous form.

When the gas is discharged from the cylinder, gases will again be discharged from the top to the bottom of the tube which insures an equal amount of mixtures throughout the cylinder as this discharge of gases takes effect. In other words, there will be a mixture of gases in the cylinder and these mixed gases will be discharged from a plurality of points by virtue of the mixed gases passing inwardly through the openings 34 and 38 thus further assuring an even mixture of different gases. Thus, an effective mixing action is carried out when the gases are forced into the cylinder and a further mixing action occurs when the gases are discharged therefrom.

By using the present invention, Stratification of the gases within the cylinder has been substantially eliminated. In fact, .a much closer blend of two gases can be accomplished without any bumping, agitating, or rolling of the cylinder and without the application of a heat or cold treatment to the cylinder itself.

In actual practice, the mixing tube of the present invention mixes gases to A of 1% accuracy which is a much higher degree of mixing accuracy than that obtained by conventional mixing practice. One important factor in forming a mixture of two or more gases is to introduce the second or subsequent gases into the mixing tube under high pressure so that the gas being discharged through the orifices at high velocity thereby creates considerable turbulence in the cylinder which actually mixes and blends the gases.

There are two methods to determine extreme accuracy in filling and mixing gases via the mixing tube process.

(1) By weight: Lets suppose gas A and gas B have the same weight factors, one pound=l% and a 95/5% mixture is required of two gases. Using gas A for and gas B for 95%, (pressures are not a factor in this step), first add five pounds (or 5%) through the mixing tube into the cylinder of gas A. Next add nineteen pounds of gas B through the mixing tube and you have a 95 (B), 5 (A) percentage mixture thoroughly mixed. (pressures from the second gas B churn up and mix, gas A into gas B). To calculate gases of different weights and/ or percentages of mixtures, merely use a slide rule. This formula would also apply for more than two gases.

(2) By volume: Lets suppose gas A and gas B have the same characteristics, 1% equals twenty pounds pressure at 70 degrees F. and a 95% mixture of two gases is required at 2,000 pounds pressure. Using gas A for 5% and gas B for 95%, first add 100 pounds gas A for 5% through the mixing tube, next add 1,900 pounds gas B for 95%. The higher pressure going into the cylinder through the mixing tube thoroughly churns up the two gases from top to bottom, giving an extremely accurate mixture, same as step one. To calculate mixing gases of different weights and/or volume bases on 70 degrees F., merely use a slide rule. This formula would also apply for more than two gases.

Gas mixtures from the cylinder are expelled bacl through the mixing tube, drawn oil? from top to bottom to further insure an accurate mixture as consumed, keeping in mind that once a gas is thoroughly mixed, using the mixing tube process, it stays at its best mixture indefinitely.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In combination with a compressed gas cylinder having means defining a single passage for entry and exhaust of gases at one end thereof, a valve controlling said passage, a mixing tube mounted solely on said means and extending longitudinally and centrally into the cylinder and terminating adjacent the other end of the cylinder, said tube being in direct communication with the passage through said means for receiving all of the gas admitted into the cylinder and all of the gas discharged therefrom, said tube including a plurality of apertures spaced longitudinally therein and along the full length thereof for enabling passage of gas between the interior of the tube and the interior of the cylinder whereby a portion of the gases will be discharged throughout the entire length of the cylinder and a portion of the gases will be received into the tube from the cylinder substantially throughout the length of the cylinder thereby mixing different gases when they are discharged into the cylinder and when they are discharged from the cylinder for use.

2. The strurture as defined in claim 1 wherein said apertures are arranged in pairs, the apertures in each pair being disposed in diametrically opposed relation, the apertures in adjacent pairs being disposed in staggered circumferential relation, the lower end of said tube having a closure plate therein, and an aperture of the same size as the apertures in the tube in said closure plate for discharging and receiving gas from the bottom end of the tube.

3. In combination with an elongated compressed gas cylinder having means defining a single passage for entry and exhaust of gases at one end thereof, a valve controlling said passage, 21 single elongated mixing tube mounted centrally within the cylinder and extending longitudinally for substantially the full length of the cylinder, said tube being in direct communication with the passage through said means for receiving all of the gas admitted into the cylinder and all of the gas discharged therefrom, said tube including a plurality of apertures spaced longitudinally therein along substantially the full length thereof for enabling passage of gas between the interior of the tube and the interior of the cylinder whereby a portion of the gases will be discharged throughout the entire length of the cylinder and a portion of the gases will be received into the tube from the cylinder substantially throughout the length of the cylinder thereby mixing difierent gases when they are discharged into the cylinder and when they are discharged from the cylinder for use, said apertures being arranged in pairs, the apertures in each pair being disposed in substantial diametrically opposed relation, the apertures in adjacent pairs being disposed in staggered circumferential relation, the lower end of said tube having a downwardly directed aperture therein for discharging and receiving gas from the bottom end of said tube.

References Cited by the Examiner UNITED STATES PATENTS 2,396,578 3/1946 Kittel et al. 259-4 X 2,521,334 9/1950 Boerstra 259 X 2,693,418 11/1954 Smith 14l'20 X 2,746,258 5/1956 Hagans 141-20 X WALTER A. SCHEEL, Primary Examiner.

I. S. SHANK, Examiner. 

1. IN COMBINATION WITH A COMPRESSED GAS CYLINDER HAVING MEANS DEFINING A SINGLE PASSAGE FOR ENTRY AND EXHAUST OF GASES AT ONE END THEREOF, A VALVE CONTROLLING SAID PASSAGE, A MIXING TUBE MOUNTED SOLELY ON SAID MEANS AND EXTENDING LONGITUDINALLY AND CENTRALLY INTO THE CYLINDER AND TERMINATING ADJACENT THE OTHER END OF THE CYLINDER, SAID TUBE BEING IN DIRECT COMMUNICATION WITH THE PASSAGE THROUGH SAID MEANS FOR RECEIVING ALL OF THE GAS ADMITTED INTO THE CYLINDER AN ALL OF THE GAS DISCHARGED THEREFROM, SAID TUBE INCLUDING A PLURALITY OF APERTURES SPACED LONGITUDINALLY THEREIN AND ALONG THE FULL LENGTH THEREOF FOR ENABLING PASSAGE OF GAS BETWEEN THE INTERIOR OF THE TUBE AND LTHE INTERIOR OF THE CYLINDER WHEREBY A PORTION OF THE GASES WILL BE DISCHARGED THROUGHOUT THE ENTIRE LENGTH OF THE CYLINDER AND A PORTION OF THE GASES WILL BE RECEIVED INTO THE TUBE FROM THE CYLINDER SUBSTANTIALLY THROUGHOUT THE LENGTH OF THE CYLINDER THEREBY MIXING DIFFERENT GASES WHEN THEY ARE DISCHARGED INTO THE CYLINDER AND WHEN THEY ARE DISCHARGED FROM THE CYLINDER FOR USE. 